This invention relates to prosthetic cardiac and venous valves and a single catheter device and minimally invasive techniques for percutaneous and transluminal valvuloplasty and prosthetic valve implantation.

The present invention relates generally to implantable prosthetic cardiac and venous valves. More particularly, the present invention pertains to prosthetic cardiac and venous valve implants which are capable of being delivered using endovascular techniques and being implanted at an intracardiac or intravenous site without the need for anatomic valve removal. The prosthetic valves of the present invention are well-suited for cardiac delivery via a femoral or subclavian artery approach using a delivery catheter, and, depending upon the specific configuration selected, may be deployed within the heart to repair valve defects or disease or septal defects or disease. According to one embodiment of the invention, there is provided a chamber-to-vessel (CV) configuration which is particularly well-suited as an aortic valve prosthesis to facilitate blood flow from the left ventricle to the aorta. In a second embodiment, there is provided a prosthetic valve in a chamber-to-chamber (CC) configuration which is particularly well-adapted for mitral valve replacement or repair of septal defects. Finally, a third embodiment is provided in a vessel-to-vessel (VV) configuration, which is well suited for venous valve exclusion and replacement.
Common to each of the CV, CC and VV embodiments of the present invention are a stent support member, a graft member which covers at least a portion of either or both the lumenal and ablumenal surfaces of the stent, valve flaps which are formed either by biological xenograft valves, synthetic valves formed from either the same material or a different material as the graft member, the valve flaps being coupled to the stent in a manner which biases the valve flaps so they close upon a zero pressure differential across the valve region.
It is important for the present invention to provide orientational definitions. For purposes of the present invention, references to positional aspects of the present invention will be defined relative to the directional flow vector of blood flow through the implantable device. Thus, the term xe2x80x9cproximalxe2x80x9d is intended to mean on the inflow or upstream flow side of the device, while xe2x80x9cdistalxe2x80x9d is intended to mean on the outflow or downstream flow side of the device. With respect to the catheter delivery system described herein, the term xe2x80x9cproximalxe2x80x9d is intended to mean toward the operator end of the catheter, while the term xe2x80x9cdistalxe2x80x9d is intended to mean toward the terminal end or device-carrying end of the catheter.
The prior art discloses certain common device segments inherently required by a percutaneous prosthetic valve: an expandable stent segment, an anchoring segment and a flow-regulation segment.
Prior art percutaneous prosthetic valve devices include the Dobben valve, U.S. Pat. No. 4,994,077, the Vince valve, U.S. Pat. No. 5,163,953, the Teitelbaum valve, U.S. Pat. No. 5,332,402, the Stevens valve, U.S. Pat. No. 5,370,685, the Pavcnik valve, U.S. Pat. No. 5,397,351, the Taheri valve, U.S. Pat. No. 5,824,064, the Anderson valves, U.S. Pat. Nos. 5,411,552 and 5,840,081, the Jayaraman valve, U.S. Pat. No. 5,855,597, the Besseler valve, U.S. Pat. No. 5,855,601, the Khosravi valve, U.S. Pat. No. 5,925,063, the Zadano-Azizi valve, U.S. Pat. No. 5,954,766, and the Leonhardt valve, U.S. Pat. No. 5,957,949. Each of these pre-existing stent valve designs has certain disadvantages which are resolved by the present invention.
The Dobben valve has a disk shaped flap threaded on a wire bent like a safety pin to engage the vessel wall and anchor the valve. A second embodiment uses a stent of a cylindrical or crown shape that is made by bending wire into a zigzag shape to anchor the device and attach the flow regulator flap. The device presents significant hemodynamic, delivery, fatigue and stability disadvantages.
The Vince valve has a stent comprised of a toroidal body formed of a flexible coil of wire and a flow-regulation mechanism consisting of a flap of biologic material. Numerous longitudinal extensions within the stent are provided as attachment posts to mount the flow-regulation mechanism. The device requires balloon expansion to deliver to the body orifice. The main shortcoming of this design is delivery profile. Specifically, the device and method put forth will require a 20+ French size catheter (approximately 9 French sizes to accommodate the balloon and 14+ French sizes to accommodate the compressed device) making the device clinically ineffective as a minimally invasive technique. Additionally, the device does not adequately address hemodynamic, stability and anchoring concerns.
The Teitelbaum valve is made of shape memory nitinol and consists of two components. The first component is stent-like and comprised of a meshwork or braiding of nitinol wire similar to that described by Wallsten, U.S. Pat. No. 4,655,771, with trumpet like distal a proximal flares. The purpose of the stent is to maintain a semi-ridged patent channel through the diseased cardiac valve after initial balloon dilation. The flared ends are intended to maintain the position of the stent component across the valve thereby anchoring the device. Embodiments for the flow-regulation mechanism include a sliding obturator and a caged ball both which are delivered secondary to the stent portion. The disadvantages of the device are the flow regulators reduce the effective valve orifice and generate sub-optimal hemodynamic characteristics; fatigue concerns arise from the separate nature of the stent and flow-regulation components; the high metal and exposed metal content raises thrombogenesis, valvular stenosis and chronic anticoagulation concerns; and the separate delivery requirements (although addressing the need for small delivery profile) in addition to any initial valvuloplasty performed increases the time, costs, risks, difficulty and trauma associated with the percutaneous procedure.
The Pavcnik valve is a self-expanding percutaneous device comprised of a poppet, a stent and a restraining element. The valve stent has barbed means to anchor to the internal passageway. The device includes a self-expanding stent of a zigzag configuration in conjunction with a cage mechanism comprised of a multiplicity of crisscrossed wires and a valve seat. The disadvantages of the device include large delivery profile, reduced effective valvular orifice, possible perivalvular leakage, trauma-inducing turbulent flow generated by the cage occlusive apparatus and valve seat, thrombogenesis, valvular stenosis, chronic anticoagulation, problematic physiological and procedural concerns due to the barb anchors and complex delivery procedure that includes inflation of occlusive member after initial implantation.
Stevens discloses a percutaneous valve replacement system for the endovascular removal of a malfunctioning valve followed by replacement with a prosthetic valve. The valve replacement system may include a prosthetic valve device comprised of a stent and cusps for flow-regulation such as a fixed porcine aortic valve, a valve introducer, an intraluminal procedure device, a procedure device capsule and a tissue cutter. The devices disclosed indicate a long and complex procedure requiring large diameter catheters. The valve device disclosed will require a large delivery catheter and does not address the key mechanisms required of a functioning valve. Additionally, the device requires intraluminal-securing means such as suturing to anchor the device at the desired location.
The Taheri valve describes an aortic valve replacement combined with an aortic arch graft. The devices and percutaneous methods described require puncture of the chest cavity.
Anderson has disclosed various balloon expandable percutaneous prosthetic valves. The latest discloses a valve prosthesis comprised of a stent made from an expandable cylindrical structure made of several spaced apices and an elastically collapsible valve mounted to the stent with the commissural points of the valve mounted to the apices. The device is placed at the desired location by balloon expanding the stent and valve. The main disadvantage to this design is the 20+ French size delivery requirement. Other problems include anchoring stability, perivalvular leakage, difficult manufacture and suspect valve performance.
The Jayaraman valve includes a star-shaped stent and a replacement valve and/or replacement graft for use in repairing a damaged cardiac valve. The device is comprised of a chain of interconnected star-shaped stent segments in the center of which sits a replacement valve. The flow-regulation mechanism consists of three flaps cut into a flat piece of graft material that is rolled to form a conduit in which the three flaps may be folded inwardly in an overlapping manner. An additional flow-regulation mechanism is disclosed in which a patch (or multiple patches) is sutured to the outside of a conduit which is then pulled inside out or inverted such that the patch(s) reside on the fully inverted conduit. A balloon catheter is required to assist expansion during delivery. The disadvantages of this design include lack of sufficient anchoring mechanism; problematic interference concerns with adjacent tissues and anatomical structures; fatigue concerns associated with the multiplicity of segments, connections and sutures; lack of an adequately controlled and biased flow-regulation mechanism; uncertain effective valve orifice, difficult manufacture; balloon dilation requirement; complex, difficult and inaccurate delivery and large delivery profile.
The Besseler valve discloses methods and devices for the endovascular removal of a defective heart valve and the replacement with a percutaneous cardiac valve. The device is comprised of a self-expanding stent member with a flexible valve disposed within. The stent member is of a self-expanding cylindrical shape made from a closed wire in formed in a zigzag configuration that can be a single piece, stamped or extruded or formed by welding the free ends together. The flow-regulation mechanism is comprised of an arcuate portion which contains a slit (or slits) to form leaflets and a cuff portion which is sutured to and encloses the stent. The preferred flow regulator is a porcine pericardium with three cusps. An additional flow regulator is described in which the graft material that comprises the leaflets (no additional mechanisms for flow-regulation) extends to form the outer cuff portion and is attached to the stent portion with sutures. The anchoring segment is provided by a plurality of barbs carried by the stent (and therefor penetrating the cuff-graft segment). Delivery requires endoluminal removal of the natural valve because the barb anchors will malfunction if they are orthotopically secured to the native leaflets instead of the more rigid tissue at the native annulus or vessel wall. Delivery involves a catheter within which the device and a pusher rod are disposed. The disadvantages of the device are lack of a well defined and biased flow-regulation mechanism, anatomic valve removal is required thereby lengthening the procedure time, increasing difficulty and reducing clinical practicality, trauma-inducing barbs as described above and the device is unstable and prone to migration if barbs are omitted.
The Khosravi valve discloses a percutaneous prosthetic valve comprised of a coiled sheet stent similar to that described by Derbyshire, U.S. Pat. No. 5,007,926, to which a plurality of flaps are mounted on the interior surface to form a flow-regulation mechanism that may be comprised of a biocompatible material. The disadvantages of this design include problematic interactions between the stent and flaps in the delivery state, lack of clinical data on coiled stent performance, the lack of a detailed mechanism to ensure that the flaps will create a competent one-directional valve, lack of appropriate anchoring means, and the design requirements imposed by surrounding anatomical structures are ignored.
The Zadno-Azizi valve discloses a device in which flow-regulation is provided by a flap disposed within a frame structure capable of taking an insertion state and an expanded state. The preferred embodiment of the flow-regulation mechanism is defined by a longitudinal valve body made of a sufficiently resilient material with a slit(s) that extends longitudinally through the valve body. Increased sub-valvular pressure is said to cause the valve body to expand thereby opening the slit and allowing fluid flow there through. The valve body extends into the into the lumen of the body passage such that increased supra-valvular pressure will prevent the slit from opening thereby effecting one-directional flow. The device includes embedding the frame within the seal or graft material through injection molding, blow molding and insertion molding. The disadvantages of the device include the flow-regulation mechanism provides a small effective valve orifice, the turbidity caused by the multiple slit mechanisms, the large delivery profile required by the disclosed embodiments and the lack of acute anchoring means.
Finally, the Leonhardt valve is comprised of a tubular graft having radially compressible annular spring portions and a flow regulator, which is preferably a biological valve disposed within. In addition to oversizing the spring stent by 30%, anchoring means is provided by a light-activated biocompatible tissue adhesive is located on the outside of the tubular graft and seals to the living tissue. The stent section is comprised of a single piece of superelastic wire formed into a zigzag shape and connected together by crimping tubes, adhesives or welds. A malleable thin-walled, biocompatible, flexible, expandable, woven fabric graft material is connected to the outside of the stent that is in turn connected to the biological flow regulator. Disadvantages of this device include those profile concerns associated with biological valves and unsupported graft-leaflet regulators, a large diameter complex delivery system and method which requires multiple anchoring balloons and the use of a light activated tissue adhesive in addition to any prior valvuloplasty performed, interference with surrounding anatomy and the questionable clinical utility and feasibility of the light actuated anchoring means.
With the shortcomings of the prior art devices, there remains a need for a clinically effective endoluminally deliverable prosthetic valve that is capable of orthotopic delivery, provides a mechanically defined, biased and hemodynamically sound flow-regulation mechanism, provides sufficient force to maintain a large acute effective valvular orifice dimension which expands to a known larger effective orifice dimension, compliant with adjacent dynamic anatomical structures, does not require valve removal, does not require chronic anticoagulation treatment, meets regulatory fatigue requirements for cardiac valve prostheses, provides a low-metal high-strength stent-annulus, is surgically explantable or endoluminally removable, in addition to being able to deploy multiple valves orthotopically, provides a delivery profile which does not exceed the 12 French size suitable for peripheral vascular endoluminal delivery, combines anatomic valve exclusion and prosthetic valve delivery via a single catheter delivery system and with short duration atraumatic procedure which is easy to complete and beneficial to very sick patients.
It is, therefore, a primary of the present invention to provide a prosthetic endoluminally-deliverable unidirectional valve. The invention has multiple configurations to treat malfunctioning anatomical valves including heart and venous valves. Prosthetic cardiac valve configurations include the chamber-to-vessel for orthotopic placement at the valvular junction between a heart chamber and a vessel, and the chamber-to-chamber for orthotopic placement at the valvular junction between two heart chambers or for septal defect repair where a septal occluding member is substituted for the flow regulator valve flaps. Prosthetic venous valve configurations include the vessel-to-vessel for orthotopic or non-orthotopic placement at a valvular junction within a vessel.
The invention consists generally of a stent body member, a graft, and valve flaps. The stent body member may be fashioned by laser cutting a hypotube or by weaving wires into a tubular structure, and is preferably made from shape memory or super-elastic materials, such as nickel-titanium alloys known as NITINOL, but may be made of balloon expandable stainless steel or other plastically deformable stent materials as are known in the art, such as titanium or tantalum, or may be self-expanding such as by weaving stainless steel wire into a stressed-tubular configuration in order to impart elastic strain to the wire. The graft is preferably a biocompatible, fatigue-resistant membrane which is capable of endothelialization, and is attached to the stent body member on at least portions of either or both the lumenal and ablumenal surfaces of the stent body member by suturing to or encapsulating stent struts. The valve leaflets are preferably formed by sections of the graft material attached to the stent body member.
The stent body member is shaped to include the following stent sections: proximal and distal anchors, a intermediate annular stent section, and at least one valve arm or blood flow regulator struts. The proximal and distal anchor sections are present at opposing ends of the prosthesis and subtend either an acute, right or obtuse angle with a central longitudinal axis that defines the cylindrical prosthesis. In either the CV or CC configurations, the proximal anchor is configured to assume approximately a right angle radiating outward from the central longitudinal axis of the prosthesis in a manner which provides an anchoring flange. When being delivered from a delivery catheter, the proximal anchor is deployed first and engages the native tissue and anatomical structures just proximal to the anatomic valve, such as the left ventricle wall in the case of retrograde orthotopic delivery at the aortic valve. Deployment of the proximal anchor permits the intermediate annular stent section to be deployed an reside within the native valve annular space and the ablumenal surface of the intermediate annular stent section to abut and outwardly radially compress the anatomic valve leaflets against the vascular wall. The distal anchor is then deployed and radially expands to contact the vascular wall and retain the prosthesis in position, thereby excluding the anatomic valve leaflets from the bloodflow and replacing them with the prosthetic valve leaflets.
Flow regulation in the inventive stent valve prosthesis is provided by the combination of the prosthetic valve leaflets and the valve arms and is biased closed in a manner similar manner to that described for a surgically implanted replacement heart valve by Boretos, U.S. Pat. No. 4,222,126. The valve regulator-struts are preferably configured to be positioned to radiate inward from the stent body member toward the central longitudinal axis of the prosthesis. The graft-leaflet has the appearance of a partially-everted tube where the innermost layer, on the lumenal surface of the stent body member, forms the leaflets and the outer-most layer, on the ablumenal surface of the stent body member, forms a sealing graft which contacts and excludes the immobilized anatomical valve leaflets. The struts of the stent are encapsulated by the outer graft-membrane. The valve regulator-struts are encapsulated by the inner leaflet-membrane and serve to bias the valve to the closed position. The regulator-struts also prevent inversion or prolapse of the otherwise unsupported leaflet-membrane during increased supra-valvular pressure. The inner leaflet-membrane may also be attached to the outer graft-membrane at points equidistant from the valve strut-arms in a manner analogous to that described for a surgically implanted replacement heart valve by Cox, U.S. Pat. No. 5,824,063. The combination of the thin walled properties of the leaflet-membrane, the one-sided open lumen support of the intermediate annular stent section, the free ends of the valve leaflets, the biasing and support provided by the valve regulator-struts and the attachment points all work to provide a prosthetic valvular device capable of endoluminal delivery which simulates the hemodynamic properties of a healthy anatomical cardiac or venous valve.

Endoluminal cardiac and venous valve prostheses and methods of manufacture and delivery thereof


A three-dimensional viewer employs adjustable diameter pinholes with the distance between the pinholes being adjustable each of the pinholes having an optical axis which is aligned with illocal frames, the spacing between the frames also being adjustable.

1. Field of the Invention
The present invention relates to devices for viewing two dimensional photographs or images (such as TV or movies) which then appear to the viewer as three-dimensional. The device is light in weight and has three basic adjustments for establishing the stereoscopic effect. These adjustments are for area of view along the optic axis, for interpupillary distance between the eyes of the viewer, and for the optic axes, themselves. As will be described below, the device is seen to enhance the quality of VCR images generated during playback.
2. Description of the Prior Art
Hand held devices to achieve an apparent three-dimensional display from ordinary two dimensional visual data such as photographs or television displays are known in the prior art. Many of these devices operate in accordance with the teachings of the Ames U.S. Pat. No. 2,542,789. That patent discloses that definite and true depth discrimination may be induced by the differentiating dispostion of some characteristic form elements in the respective dioptric images, irrespective of their position on the retina. U.S. Pat. Nos. 607,172; 1,636,450; 2,297,322; and 2,337,139 show the implementations of the Ames description by tilting one image relative to another with mirrors or refractive elements. U.S. Pat. No. 2,986,969 uses both refracting and polarizing elements to achieve the Ames criterion.
U.S. Pat. Nos. 3,460,882 and 4,049,339 show other techniques for creating the effect of 3-D using illocal framing and "window effect", respectively.
The major difference between the present invention and the approaches and devices of the prior art is that the present invention accomplishes surprising and unexpected results without the use of mirrors, lenses, or other optics. In fact, the results of the present invention are achieved without any other moving parts or optical elements.
The net three-dimensional effect in the present invention is the sum of four distinct and separate processes and their respective effects; but only three of the processes are independent. The first of the four processes is the observation that a strong perception of depth can be observed with only one eye (while the other eye is closed) when a two dimensional display is viewed through a tiny aperture of 1 mm or less in diameter (a "pinhole"). The second three-dimensional enhancing effect occurs when the monocular image of the first process (with its increased perception of depth) is viewed with both eyes, binocularly, by the use of a second aperture. The second effect adds to and enhances the first effect. The third process is that of illocal framing which is implemented by employing frames suspended between the display and the observer. However, the use of the illocal framing concepts implemented in the present invention depends solely on the increased depth of field afforded by the use of the pinholes described above.
As discussed in the aforementioned U.S. Pat. No. 3,460,882 by Abrahamson, "illocal framing" is visible framing that is situated in a plane substantially removed from that of the observed picture itself and near the observer. "Illocal framing" is in contrast to standard framing which is local to the picture it enclosed, or is in direct contact with it. The illocal frame appears situated somewhere between the picture and the observer and has the capability of improving the depth effects. The objects in the picture appear to be more life-size.
The three-dimensional viewing glasses implements illocal framing by positioning the frames by adjusting H, the distance from the pinhole to the frames, within the increased depth of focus range determined by the pinhole diameter. The depth of focus depends on the pinhole diameter but also on the distance of the fixation point from the eye, Physiology of the Eye, Hugh Davson, Academic Press, N.Y., 1980, Page 486. The display is located at the fixation point. With H either within the depth of focus range or close to it, the frames will be, respectively, in focus or almost in focus along with the display under observation. The requirement of illocal framing, to suspend a frame between the observer and the display, is thus met by the use of a pinhole to extend the depth of focus range and allow the frames to come into the same depth of focus range occupied by the display.
An important visual property of the three-dimensional viewing glasses in the "movie theatre effect". A pair of correctly focuses glasses will give the wearer the distint "viewpoint" that he or she is actually inside a movie theatre where the frames now appear as a full size movie screen appearing to be approximately 100 feet away and the theatre's "ceiling" and "walls" (actually, the inside of the input aperture housings) are in their proper perspective and depth relationships as they would be in a real movie theatre.
This effect is caused by three factors. The increased depth of focus afforded by the pinhole, the illocal framing effect of the picture appearing to be more than life size and the visual isolation from the environment afforded by the ambient light shield. The movie theatre effect is especially important when viewing television displays if optimum results are despred.
The fourth process under consideration, is, I believe, a new way of applying and implementing the principles of the Ames U.S. Pat. No. 1,636,450. That patent recognized that an illusory depth or rotundity is caused by the modification of the direction of the viewing axis of one or both eyes. Typically, this is done with the use of refraction and reflection elements as previously discussed. In my invention, modification of the viewing axis is accomplished by spatially positioning a pinhole which defines the optical axis and thus the location of images on the retina. As the pinhole has a three-dimensional effect all of its own, an important part of my invention is the alteration of the viewing axes of the eyes by positioning the pinholes.
Even without pinholes, any obstruction, such as a finger or a half inch wide by two inch long strip of opaque tape, which is placed in close proximity to the eye and is edged slowly into the eyes' field of view will also change the direction of the viewing axis. This effect is not readily observed when done to one eye alone due to the tendancy of the eye to compensate for the restriction in its field by adducting. This is discussed in Physiology of the Eye, H. Davson, Academic Press 1980, p. 520. When done symmetrically and slowly to both eyes simultaneously, a surprisingly excellent three-dimensional representation of two dimensional material will be displayed. By symmetric, it is meant that one obstruction is moved simultaneously into the field of view of the right eye from the left side of the right eye while in the left eye, an obstruction is moved into its field of view from the right side of the left eye. Once stereopsis is detected, the position of the obstruction is maintained. Excessive vignetting is apparent at first but can be minimized with practice.
Stereopsis generated in this manner is caused by a temporal disparity. If however, the obstructions in the above example were symmetrically moved from the temple side (i.e., both left and right temples simultaneously) towards the nasal side, a condition of nasal disparity would be created resulting in "locally inverted" or "locally pseudoscopic like" images. These same effects are also apparent when pinholes are used. The main difference between the two stereo producing techniques is the magnitude of the image vignetting. Vignetting is unavoidable in the case of the obstruction technique and non-existant when using the present invention properly focused.
For a given distance between the device (i.e., its pinhole) and the two-dimensional display under observation, the interpupillary distance, d.sub.i, is adjusted for maximum light throughput, d.sub.mlt. Under these conditions, the observed stereopsis is due soleley to the above mentioned effects and not on the teachings of the Ames patent. When d.sub.i is equal to d.sub.mlt, it is assumed that the axial directions of the eyes are equal to the axial directions that would occur if the two-dimensional display were viewed normally without the three-dimensional viewing glasses of the invention. However, by increasing the interpupillary distance beyond d.sub.mlt, a modification in the direction of the viewing axes of one or both eyes will occur. Under these conditions, the Ames teachings will now apply and the observed stereopsis will increase dramatically with increasing d.sub.i until a condition analogous to hyperstereopsis is reached. Though not necessary, the frames should be readjusted for each setting of the interpupillary distance, d.sub.i. Adjusting the frames enables the principles of illocal framing. Counteracting the increasing stereopsis as d.sub.i is increased are increased image vignetting and a reduction in light throughput for larger values of d.sub.i greater that d.sub.mlt.
In actual use, knowledge or determination of d.sub.mlt is not required for the correct use or adjustment of my invention. however, d.sub.mlt may be determined by looking through the device with its pinholes wide open. While fixating on the display of interest, d.sub.i is adjusted to that size which gives a normal flat display. With the device so adjusted, the point of fixation is said to lie on the horopter and for a given fixation distance will simulate corresponding retinocortical elements.
The selected value of d.sub.mlt may be verified by closing the pinhole down to about 1 mm and adjusting d.sub.i for the minimum three-dimensional effect without image "inversion", This process is hindered by the presence of monocular depth perception introduced by the small 1 mm diameter pinhole. Values of d.sub.mlt selected by the latter method are often within .+-.0.6 mm of the first method.
On the preferred embodiment of my invention, the maximum diameter when wide open was 4.7 mm. This diameter was small enough to be present in the observer's peripheral field of view and cause stereopsis with vignetting as was noted above to occur when an obstruction is symmetrically introduced into the peripheral field of view. Centering the irises within the wide open pinholes will eliminate this extraneous stereopsis, if present.
For d.sub.i less then d.sub.mlt contiguous portions of the observed image will appear "inverted" or "locally pseudoscopic" wherein image elements appearing in the foreground when d.sub.i is greater that d.sub.mlt will now appear in the background and vice versa. This effects is not observed in television displays due to their relatively low spatial resolution. This local pseudoscopic effect can be shown to exist even when the photographic display under consideration consists only of contiguous color differences with no perspective information.
Of the three independent processes under discussion, the pinhole process plays the key role. This is because the pinhole process is in effect at all times, while the other two processes, Ames and illocal framing, are not. In addition, the pinhole process allows the "seamless" integration of all three independent processes without the use of optical elements.
The small pinhole aperture selected achieves a number of beneficial results in the invention. The pinhole increases the observer's depth of focus thereby reducing the accommodating capability of the single eye. Elimination of accommodation results in improved monocular depth sensation.
The pinhole aperture increases the sharpness of any given display in addition to reducing noise in television images because of five interrelated factors which include:
1. The fact that light passing through a pinhole is, in a sense, automatically focused where the focal length of the pinhole is defined as the square of the diameter of the pinhole divided by the wavelength of the transmitted light. See M. Young, PInhole Optics, Applied Optics, Vol. 10, No. 12. Dec. 1971, p. 2764;
2. The increase in depth of focus due to the reduction in pupil size;
3. The spatial smoothing (i.e. low pass optical spatial filtering) of the television image caused by restricting the optical spatial frequencies entering the eye by decreasing the diameter of the exit pupil (i.e., the pinhole). This cut off eliminates those spatial frequencies responsible for high resolution image detail (i.e., video noise). With these high frequency components removed, their associated noise will be filtered components removed, their associated noise will be filtered from the image recorded on the retina;
4. The measured increase in the response of the Modulation Transfer Function of the refractive optics of the human eye as the pinhole is closed down from its wide open position (of about 5 mm) to a limiting diameter of 3 mm. Ian Overington, Vision and Acquisition, Pentech Press, London/Crane, Russak & Co. Inc., N.Y., 1976, p. 12;
5. A reduction in the veiling glare entering the eye.
The three-dimensional viewing glasses improves the overall appearance of a color television display and is especially effective during the playback of recorded VCR (video cassette recorder) images. Observing a television display through the device results in a visual smoothing (i.e., a spatial averaging) of the image where television raster lines and finely structured time dependant white speckled noise are substantially reduced. The reduction of this noise results in an apparent improvement in the resolution of the video display in spite of an objectively measured loss in resolution. It has been mentioned (Overington, p. 188) that with noisy pictorial displays and television pictures, blurring results in an increase in the detail information visualized in the display. Television is particularly sensitive to this effect.
An actual loss in resolution can be objectively measured by illuminating a standard resolution target and observing it from a distance of 1.6 meters. In this test, lines separated at 1 mm could be easily resolved without the pinholes but could not be resolved with the 0.8 mm diameter pinholes in place.
When located in as close proximity to the cornea as possible, the pinhole will largely negate the use of the viewer's cornea and lens. However, some residual focusing (or accommodation) is still possible by the eye's lens (Hennessy, R.T., Iida, T., Shina, K., Leibowitz, H.W., "The Effect of Pupil Size on addommodation", Vision Res., Vol. 16, pp. 587-589, 1976).
Pinhole images are inverted and at a fixed distance from the pinhole to the retina, focusing is accomplished by closing the pinhole to improve the depth of field. Because of the five factors under discussion, persons wearing mild prescription eyeglasses who remove them to use the three-dimensional viewing glasses of the invention may experience a significant improvement in normal visual resolution over that received had they worn no eyeglasses. In most instances, these viewers will experience and improvement in normal visual resolution equal to that received with their own prescription eyeglasses. For one observer with +0.5 diopter corrective lenses, this optimum resolution occurred at a pinhole diameter of 1.1 to 1.2 mm at a 1.6 meter viewing distance. The object viewed was a standard test target. Smaller pinhole diameters worsened the resolution at this 1.6 meter viewing distance. However, this was not true for a television image viewed at this same distance. In this instance, the apparent resolution of the video image continues to improve as the pinhole is reduced. Optimum video resolution was obtained with a pinhole diameter of 0.8 to 0.9 mm.
Finally, the pinholes allowed the placing of an optically focused frame in front of the display in connection with the illocal framing techniques discussed above in U.S. Pat. No. 3,460,882.
For any given display, the quality of the perceived three-dimensional effect will depend on the specific requirements of the display including the display's brightness, resolution, viewing distance and image content.
In general, sharp lithographic or photographic material produces the most dramatic three-dimensional results. Television produces good results, while normal movie screen illumination levels are not sufficient for adequate operation of the three-dimensional viewing glasses. This may be corrected in principle by making provisions to increase the screen illumination levels.
Illocal framing is a necessity when viewing television displays. It can be dispensed with, however, when observing photographic of printed (lithographic) material.
When observing a 19 inch diagonal screen color television close up at viewing distances of approximately 36 inches, a small pinhole (0.70 mm) is desirable. If this same image is viewed at a distance of say 63 inches, a pinhole setting of 0.90 mm is found to be more suitable. More importantly, at either viewing distance, varying d.sub.i has virtually no effect on the resulting television image; the Ames process results in no discernable stereopsis at normal TV resolution specifications.
Typically, a small pinhole is required when observing photographic or printed material close up (15-34 inches). However, the size of this pinhole can vary between 1.10 and 0.75 mm depending on the available illumination, the resolution in the image, and the specific viewing distance.
Suitable illumination levels for pictorial material can be established by illuminating the material with a 100 to 150 Watt household light bulb positioned to eliminate specular glare at a distance of about 12 inches from the display material.
The best pinhole diameter for a standard resolution (0.20 mm dot separation) lithographic print observed at a viewing distance of 63 inches was found to be around 1.5 mm. Different results should attend different observers.
The invention can be used as a sports or scenic viewing glass since the need to refocus the eye for distant or near objects being observed is eliminated. A field of view of 30 degrees attends this mode of operation. This mode substantially reducers viewer fatigue. It is noted that the invention's increased depth of field allows ordinary objects to be examined, without fatigue, at distances closer than the normal viewing distance of 25 cm.
The principle object of the present invention is the provision of a device which results in a three-dimensional viewing system posessing a degree of stereopsis judged comparable to normal stereoscopic photography which uses two dissimilar images of the same object.
Another object of the present invention is the construction of a device of the simplest possible design employing no transmissive or reflective optical elements which add to costs, complexity, and to interference since such elements are sources of noise and are difficult to use.
A further object of the present invention is to produce a device of the class described which has extreme optical clarity.
Another object of the present invention is to provide the viewer with increased spatial resolution when the invention is used to view television.
A further object of the invention is to provide a two dimensional object with a three-dimensional perspective without the need for the viewer to wear their normal eyeglasses.
Another object of the invention is the provision of an optical device which substantially reduces playback noise in recorded VCR images resulting in an increase in the observed signal-to-noise ratio in these images when same are viewed through the invention.
A further object of the invention is the provision of a stereoscopic viewer which can be used to examine objects which are both nearby and distant without the fatigue caused by continual changes in focusing.
An additional object of the invention is the provision of a 3-D viewer which can be used to examine objects located extremely close to the viewer without the need to refocus and without the resultant fatigue.
Another object of the present invention is the provision of a two dimensional to three dimensional viewer which is light in weight to allow for comfortable mounting on the viewer's head over the eyes in the manner of goggles.
A further object of the invention is the provision of a device which provides apparent three-dimensional visual displays using ordinary two dimensional visual information such as photographs and television displays.
Another object of the invention is the generation of three-dimensional effects from two dimensional displays without the necessity for any special prerecorded visual or other information to create the 3-D effects.


Seamless multipoint label distribution protocol (mLDP) transport over a bit index explicit replication (BIER) core may be provided. First, it may be determined that a first plurality of network devices comprise BIER edge routers. Then, in response to determining that the first plurality of network devices comprise BIER edge routers, a Targeted Label Distribution Protocol (T-LDP) session may be created between a first one of the first plurality of network devices and a second one of the first plurality of network devices. Next, an address of a peer device connected to the second one of the first plurality of network devices may be advertised by the second one of the first plurality of network devices over the T-LDP session.

Multi-Protocol Label Switching (MPLS) is a type of data-carrying technique for high-performance telecommunications networks that directs data from one network node to the next based on short path labels rather than long network addresses, avoiding complex lookups in a routing table. The labels identify virtual links (paths) between distant nodes rather than endpoints. MPLS can encapsulate packets of various network protocols, hence its name "multiprotocol". MPLS supports a range of access technologies, including T1/E1, ATM, Frame Relay, and DSL.